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ABSTRACT: Si-based nanopillars of various sizes were fabricated by lateral structuring using anisotropic etching and thermal oxidation.
We obtained pillars of diameter <500nm, about 25μm in height, with an aspect ratio of more than 50. The distance between pillars was varied from 500nm to 10μm. Besides the fabrication and structural characterization of silicon nanopillars, implementation of adequate metrology for
measuring single pillars is described. Commercial tungsten probes, self-made gold probes, and piezoresistive silicon cantilever
probes were used for measurements of nanopillars in a scanning electron microscope (SEM) equipped with nanomanipulators.
KeywordsNanopillars-thermoelectrics-silicon
Journal of Electronic Materials 05/2012; 39(9):2013-2016. · 1.47 Impact Factor
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ABSTRACT: We achieved to etch nanostructures as well as structures with high aspect ratios in silicon using an inductively coupled plasma
cryogenic deep reactive ion etching process. We etched cantilevers, submicron diameter pillars, membranes and deep structures
in silicon with etch rates between 13nm/min and 4μm/min. These structures find applications as templates for metal organic
vapour phase epitaxial growth of GaN-based nanostructures for optoelectronic devices or they are the basic constituents of
a nanoparticle balance in the subnanogram range and of a thermoelectric generator.
Microsystem Technologies 04/2012; 16(5):863-870. · 0.93 Impact Factor
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ABSTRACT: In this paper, a silicon resonant cantilever sensor is used for monitoring airborne nanoparticles (NPs) by detecting the resonant frequency shift that is directly induced by an additional NPs mass deposited on it. A piezoelectric stack actuator and a self-sensing technique using a piezoresistive strain gauge are involved in the sensor system in order to actuate and detect the oscillation of cantilever sensor, respectively. The dielectrophoresis (DEP) method is employed for trapping the airborne NPs in a stable carbon aerosol assessment. A thermal-induced frequency shift is also investigated with the purpose of observing the limitation imposed by thermal effects on the minimum detectable NPs mass. The proposed sensor reveals a mass sensitivity of 8.33 Hz/ng, a fundamental resonant frequency of 43.92 kHz, a quality factor of 1230, and a temperature coefficient of the resonant frequency (TC<sub>f</sub>) of -28.6 ppm/°C. The results demonstrate a possibility of using this resonant cantilever in mobile airborne sensor applications.
Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International; 07/2011
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ABSTRACT: We report on a micro-machined resonator for mass sensing applications which is based on a silicon cantilever excited with a sputter-deposited piezoelectric aluminium nitride (AlN) thin film actuator. An inductively coupled plasma (ICP) cryogenic dry etching process was applied for the micro-machining of the silicon substrate. A shift in resonance frequency was observed, which was proportional to a mass deposited in an e-beam evaporation process on top. We had a mass sensing limit of 5.2 ng. The measurements from the cantilevers of the two arrays revealed a quality factor of 155–298 and a mass sensitivity of 120.34 ng Hz−1 for the first array, and a quality factor of 130–137 and a mass sensitivity of 104.38 ng Hz−1 for the second array. Furthermore, we managed to fabricate silicon cantilevers, which can be improved for the detection in the picogram range due to a reduction of the geometrical dimensions.
Journal of Micromechanics and Microengineering 05/2010; 20(6):064007. · 2.11 Impact Factor
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ABSTRACT: Application of a novel MEMS cantilever probe is described which is designed for non-destructive profilometry with micro machined surfaces, e.g., inside high-aspect-ratio micro bores. As an actual topic of industrial production the surface finish of diesel injector nozzle spray holes is investigated for a variety of state-of-the-art nozzle types. We address the performance of the sensor (resolution, uncertainty, speed) and the limits of the method to determine the reproducibility of a micro bore fabrication process as well as its optimization.
Industrial Technology (ICIT), 2010 IEEE International Conference on; 04/2010
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ABSTRACT: Inductively coupled plasma (ICP) cryogenic dry etching was used to etch submicron pores, nano contact lines, submicron diameter pillars, thin and thick cantilevers, membrane structures and anisotropic deep structures with high aspect ratios in silicon for bio-nanoelectronics, optoelectronics and nano-micro electromechanical systems (NMEMS). The ICP cryogenic dry etching gives us the advantage of switching plasmas between etch rates of 13 nm min−1 and 4 µm min−1 for submicron pores and for membrane structures, respectively. A very thin photoresist mask can endure at −75 °C even during etching 70 µm deep for cantilevers and 300 µm deep for membrane structures. Coating the backsides of silicon membrane substrates with a thin photoresist film inhibited the lateral etching of cantilevers during their front release. Between −95 °C and −140 °C, we realized crystallographic-plane-dependent etching that creates facets only at the etch profile bottom. By varying the oxygen content and the process temperature, we achieved good control over the shape of the etched structures. The formation of black silicon during membrane etching down to 300 µm was delayed by reducing the oxygen content.
Journal of Micromechanics and Microengineering 09/2009; 19(10):105005. · 2.11 Impact Factor
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ABSTRACT: We achieved to etch nano- and deep structures in silicon using ICP-cryogenic dry etching process. We etched nanopores and nanocantilevers with an etch rate of 13 nm/min, nanopillars with an etch rate of 2.8 μm/min - 4.0 μm/min, membrane and cantilever structures with an etch rate of 4 μm/min and 3 μm/min, respectively. Nanopores and nanocantilevers are interesting structures for Bionanoelectronics. Nanopillars can be used as substrates/templates for the MOCVD growth of GaN nanoLEDs. They are the basic constituents of a nanoparticle balance and also of a thermoelectric generator. For the joining of the silicon wafers of the thermoelectric generator the low temperature joining technique can be used. Cantilevers can be used for sensing, e.g. as tactile cantilevers. They can be used also as resonator for mass sensing even in the subnanogram region. The actuation of the resonator can be done by using piezoelectric thin films on the cantilevers. The mass detection depends on the resonance frequency shift caused by loaded mass on the cantilevers. Such cantilevers are robust and easy to produce. The deep etching in silicon was done by using a photoresist mask and creating perpendicular and smooth sidewalls.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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